OPA548F datasheet(10/24 Pages) TI

10 / 24 page

OPA548

SBOS070B

www.ti.com

THERMAL RESISTANCE vs

CIRCUIT BOARD COPPER AREA

012345

Copper Area (inches2)

OPA548F

Surface Mount Package

1oz copper

Circuit Board Copper Area

OPA548

Surface-Mount Package

FIGURE 5. TO-220 Thermal Resistance vs Aluminum Plate Area.

FIGURE 6. DDPAK Thermal Resistance vs Circuit Board Copper Area.

conducting output transistor. Power dissipation can be mini-

mized by using the lowest possible power-supply voltage

necessary to assure the required output voltage swing.

For resistive loads, the maximum power dissipation occurs at

a dc output voltage of one-half the power-supply voltage.

Dissipation with ac signals is lower. Application Bulletin

SBOA022 explains how to calculate or measure power

dissipation with unusual signals and loads.

THERMAL PROTECTION

Power dissipated in the OPA548 will cause the junction

temperature to rise. The OPA548 has thermal shutdown

circuitry that protects the amplifier from damage. The thermal

protection circuitry disables the output when the junction

temperature reaches approximately 160

°C, allowing the de-

vice to cool. When the junction temperature cools to approxi-

mately 140

°C, the output circuitry is again enabled. Depend-

ing on load and signal conditions, the thermal protection

circuit may cycle on and off. This limits the dissipation of the

amplifier but may have an undesirable effect on the load.

Any tendency to activate the thermal protection circuit indi-

cates excessive power dissipation or an inadequate heat

sink. For reliable operation, junction temperature should be

limited to 125

°C, maximum. To estimate the margin of safety

in a complete design (including heat sink) increase the

ambient temperature until the thermal protection is triggered.

Use worst-case load and signal conditions. For good reliabil-

ity, thermal protection should trigger more than 35

°C above

the maximum expected ambient condition of your applica-

tion. This produces a junction temperature of 125

°C at the

maximum expected ambient condition.

The internal protection circuitry of the OPA548 was designed

to protect against overload conditions. It was not intended to

replace proper heat sinking. Continuously running the OPA548

into thermal shutdown will degrade reliability.

234567

Aluminum Plate Area (inches2)

THERMAL RESISTANCE

vs ALUMINUM PLATE AREA

Aluminum Plate Area

Flat, Rectangular

Aluminum Plate

OPA548

TO220 Package

0.030in Al

0.062in Al

0.050in Al

Vertically Mounted

in Free Air

Optional mica or film insulator

for electrical isolation. Adds

approximately 1

°C/W.

Aluminum

Plate Thickness

OPA548F Datasheet(PDF) 10 Page - Texas Instruments

OPA548F Datasheet(HTML) 10 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL